Automotive enthusiasts frequently install modifications on their vehicles that enhance the performance of the vehicle's drivetrain. Such performance modifications can include intake manifolds allowing for less restricted airflow, modified exhaust headers, less restricted post-catalytic-converter exhaust systems, modified camshafts, ram-air intakes, cylinder head modifications, and so forth, as well as modifications to other systems of the vehicle. To conclusively determine the effects of a particular modification, it is necessary to measure the performance characteristics of the vehicle. In other instances, an owner may also wish to measure the performance characteristics of an unmodified vehicle. Typically, such measurements are performed on a dynamometer. Due to the significant cost and space requirements of dynamometers, an owner would need to take the vehicle to an automotive garage or shop.
Dynamometers typically fall into two categories: engine dynamometers and chassis dynamometers. An engine dynamometer requires that the motor be removed from the vehicle and attached to the apparatus. The engine is then accelerated with an opposing load provided by a controllable electrical or mechanical system, or a combination of the two. The acceleration is then correlated with the load and the motor torque can then be determined. If the engine shaft speed is known, the power rating of the motor can be calculated. The chassis dynamometer does not require that the engine be removed. In this case, the vehicle is placed on the dynamometer such that the drive wheels engage a roller, and an opposing load is then accelerated by the drive wheels. Based on the acceleration, load, and drive speed, the torque and power can be determined.
Both of the previously described methods present limitations, do not reflect real-world driving conditions, and are typically expensive. Removing the engine from the vehicle to use an engine dynamometer is labor-intensive, while the power losses due to the other drivetrain components are not known. A chassis dynamometer requires a qualified individual to secure the vehicle for safety, and does not account for losses due to the road surface nor the effects of actual driving conditions (such as, for example the effects of ram-air intakes). Both of the traditional methods are usually expensive and do not reflect real world driving. Furthermore, vehicle analysis systems used by original equipment manufacturers (OEMs) can be prohibitively expensive for individual or occasional use. A simple and inexpensive way of measuring vehicle performance characteristics in real-time while taking into account real-world driving conditions is therefore desired.